I thought it was interesting that the UK-based professor restricted the scope of these statements to refer to Americans. It seems that anti-vax sentiment may be the strongest in France,[1] and that it is also quite active in Italy.[2] The professor teachers US and UK politics, so I can see why he'd want to stick to his area of expertise. At the same time, his statements seem to imply that Americans are unique in these beliefs.

1: https://www.acsh.org/news/2016/09/09/france-leads-world-anti...

2: https://www.independent.co.uk/news/world/europe/anti-vaxxers...